[boost] Which forum to handle issues/questions regarding libraries

I've been studying the boost multiprecision library and I have a few questions relating to various aspects of said library. These questions are quite specific to that library and I'm not sure that they are of wider interest other than to a couple people. So I'm wondering if it would be better to post these as library issues on github or on this list or both. It used to be simple but now we have at least three places to discuss these things: slack, here and github issues for the library in question. Also sometimes some PRs can highlight differences which can get ironed out in the PR comments. Do we have a consensus as to the preferred way to select the correct forum? Robert Ramey